FIXa-triggered thrombin generation assay. Native FVIII in healthy donor samples (normal plasma; n = 40) was compared with transgene-produced FVIII-SQ in trial 270-301 (gene therapy plasma; n = 25), after individual participants (n = 7) had reached nonhemophilic CS activity levels (≥40 IU/dL) between weeks 23 and 26. Box-and-whisker plots were generated for thrombin peak height (A), ETP (B), lag time (C), and time-to-peak (D). The horizontal line in the box represents the median, the box represents the Q1 to Q3 interquartile range (IQR), and the whiskers indicate the minimum and maximum value that fell within Q1 to 1.5 × IQR and Q3 + 1.5 × IQR, respectively. Dashed horizontal lines represent the lower and upper limits of the normal reference range, respectively. P values represent significance levels from Mood’s median test.